1. Field of the Invention
The present invention relates to a radio network, wherein data flows are routed between at least one mobile station and a mobility anchor of the network and wherein the mobile station can connect to the mobility anchor using multiple network interfaces simultaneously. Further, the present invention relates to a method for operating a radio network, especially for routing data flows within the network, wherein data flows are routed between at least one mobile station and a mobility anchor of the network and wherein the mobile station can connect to the mobility anchor using multiple network interfaces simultaneously.
2. Description of the Related Art
Radio networks of the above type are known from different applications. Current standards for network based mobility are obtainable from S. Gundavelli, K. Leung, V. Devarapalli, K. Chowdhury, B. Patil, Proxy Mobile IPv6, RFC 5213, August 2008. Such standards have limited support for multi-mode enabled mobile-stations according to V. Devarapalli, N. Kant, H. Lim, C. Vogt, Multiple Interface Support with Proxy Mobile IPv6, draft-devarapalli-netlmm-multihoming-03.txt, work in progress, August 2008, which can attach to the network infrastructure using multiple network interfaces simultaneously. The benefit of enabling such operation mode is to provide enhanced services such as flow distribution, load sharing, network resilience or aggregation of wireless bandwidth.
These enhanced services require mechanisms to perform forwarding decisions based on routing policies, for uplink and downlink traffic within a local domain. Use of multiple PDN (Packet Data Network) connections simultaneously to route data flows are currently design requirements and accepted work items in the 3GPP (Third Generation Partnership Project) standardization body. However, the considered use cases focus on limited and static configuration of routing policies, see for example 3GPP SA WG2, TD S2-086386, Work Item Description for Multi Access PDN connectivity and IP Flow Mobility, August 2008. Dynamic routing policies and some associated use cases require the set up of routing policies on both, mobile stations and network components, such as the Packet Data Network (PDN) Gateway. Both, the mobile station and its mobility anchor need to be synchronized regarding the current routing policies allowing for uplink and downlink traffic regarding one flow to use the same interface.
Such mechanisms are not considered in the current state of the art within 3GPP where the PCC (Policy and Charging Control) component—see 3GPP TS 23.203, V8.2.0, Policy and Charging Control Architecture (Release 8)—provides a mechanism to enforce Quality-of-Service (QoS) control and charging on designated gateways in the network but provides no information regarding routing policies. This is in particular a problem for network-based mobility management, as a direct interface between the mobile terminal and the relevant component for routing policy enforcement is not foreseen.
From 3GPP TS 23.228, V8.6.0, IP Multimedia Subsystem, Stage 2(Release 8) are obtainable IP Multimedia Subsystems (IMS) which can be part of the above mentioned network environments.
A mobile station or a multi-mode User Equipment (UE), which has multiple radio interfaces, attaching to such a network would normally be assigned different network prefixes for each interface and thus configure itself with a different IP address on each interface. In this situation any session starting over an interface would have all respective flows routed through/from the same interface and each interface would be considered in a separate entry at the PDN GW (Packet Data Network Gateway).
Regarding more advanced scenarios, where the network assigns the same network prefix to the UE and it is allowed to configure the same IP address on both interfaces, there is currently no mechanism to allow the PDN GW to decide, for example, on which Serving GW (Gateway) to forward a downlink flow without any further policies. In the current scenario, no aggregation or distribution of flows over different interfaces is considered.